In general, an electric hair cutting apparatus includes a fixed primary blade and a secondary reciprocating blade. A motor causes the reciprocating blade to move side-to-side with respect to the fixed blade, trimming any hair therebetween. Often, an eccentric is used to translate straight-line rotation created by the motor into the side-to-side motion needed to move the reciprocating blade. A shaft from the motor, which rotates about its central longitudinal axis, is generally connected to the eccentric. In some constructions, the shaft is connected to the eccentric at a position which is off-center from the central axis of the eccentric, such that rotation of the shaft causes the eccentric to revolve around an axis other than the central axis of the eccentric. This off-center rotation of the eccentric can be used to induce side-to-side motion of the reciprocating blade.
However, mechanically translating the rotational motion of the eccentric into side-to-side motion generally involves physically contacting the eccentric (or a flange extending from the eccentric) with another component, such as a drive tip, which drives the reciprocating blade. As the eccentric rotates, it physically pushes on the drive tip, creating a point of wear. Further, maintaining proper contact between the eccentric and the drive tip can be somewhat difficult. The wear and tear, as well as loose hair build-up can cause inefficient or ineffective contact with the eccentric.
Further, as the eccentric rotates, it inherently creates a moving center of mass for the clippers. This is felt as a vibration to the user, due to the high RPM at which the eccentric is rotating. Such vibration is undesirable to users.
It is therefore desirable to provide a hair cutting apparatus with less wear and tear on the internal components, and which exhibits less vibration during use.